Make some strings easier to translate and add support for multiple mod authors

This PR aims to make some strings easier to translate. There are some places where strings are just sticked together instead of using proper format strings. From the view of a translators, such strings can be a bit tedious to translate. This PR reorganizes some strings to format strings. This PR thus tackles #4658 at least partly.

Included in this PR is support for multiple authors in mods, refer to <https://github.com/Wuzzy2/Cataclysm-DDA/commit/775e9e4a81b28460fe4b37ea4bc0fbb91de3d89b> to see an explanation.